Vitamin D3 (Cholecalciferol)

One of the most evidence-based supplements overall. Deficiency is extremely common. Regular supplementation reduces all-cause mortality in meta-analyses.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

Large meta-analyses (VITAL, etc.) confirm fracture reduction, reduced respiratory infections, and modest all-cause mortality reduction. Deficiency associated with depression, autoimmunity, and cancer risk. D3 is 2–3x more effective than D2 at raising serum levels.

• Essential for calcium absorption and bone health
• Modulates innate and adaptive immune function
• Meta-analyses show reduced all-cause mortality
• May reduce risk of respiratory infections

1000–5000 IU daily for most adults. Dose based on serum 25(OH)D levels. Take with fat-containing meal.

• Hypercalcemia at chronic high doses
• Nausea and vomiting (toxicity)
• Kidney stones with excess calcium

Toxicity possible at chronic intake above 10,000 IU/day (hypercalcemia). Monitor 25(OH)D levels. K2 co-supplementation recommended at high doses.

Optimal serum level debated (30–60 ng/mL commonly recommended). Individual response varies with body weight, skin color, and sun exposure.

• Immunity75
• Longevity70
• Mood45
• Muscle35